Sony Minolta 20mm f/2.8
Full-Frame for Sony Alpha & Minolta MAXXUM Mounts
For Sony E-Mount with Sony LA-EA4
World's First AF Ultrawide (1986-)
Performance Compared Recommendations
Minolta Maxxum 20mm f/2.8 (Covers full-frame, for Sony Alpha and Minolta MAXXUM cameras, metal 72mm filter thread, 10.0 oz./284 g, about $225 used if you know How to Win at eBay). enlarge. I got mine at this direct link to them at eBay.
This all-content, junk-free website's biggest source of support is when you use those or any of these links to approved sources when you get anything, regardless of the country in which you live. Buy only from the approved sources I use myself for the best prices, service, return policies and selection. Thanks for helping me help you! Ken.
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Sample Images
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Seven Palms Oasis, 13 July 2017. Sony A9 with Sony LA-EA4 adapter, Sony Minolta 20mm f/2.8 at f/18 at 1/30 hand-held at Auto ISO 100. bigger or camera-original © file.
Seven Palms Oasis, 09 July 2017. Sony A9 with Sony LA-EA4 adapter, Sony Minolta 20mm f/2.8 at f/11 at 1/20 hand-held at Auto ISO 100. bigger or full-resolution.
Tower 29, 23 May 2013. (Sony A99, Minolta MAXXUM AF 20mm f/2.8, f/11 at 1/200 at Auto ISO 100.) bigger or Full-Resolution.
Hacienda, July 2017. Sony A9 with Sony LA-EA4 adapter, Sony Minolta 20mm f/2.8 at f/16 at 1/125 at Auto ISO 100. bigger or full-resolution.
Desert Pool, July 2017. Sony A9 with Sony LA-EA4 adapter, Sony Minolta 20mm f/2.8 at f/11 at 1/125 at Auto ISO 100. bigger or full-resolution.
Introduction
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This is a Minolta lens, but Sony bought Minolta in 2006 and has since sold the same products as Sony.
This Sony Minolta 20mm f/2.8 is a very well made ultrawide lens for all Sony Alpha and Minolta MAXXUM cameras. Use it with the Sony LA-EA4 adapter and it becomes a Sony E-Mount lens for Sony's hottest mirrorless cameras!
Unlike the mostly plastic Sony and Nikon 20mm lenses today, this Minolta has a metal filter thread, metal hood mount and metal focus ring. Ha!
This MAXXUM 20mm AF has rear-group focusing, which means that nothing moves externally (except the focus ring) when focused. The front of this lens is solid metal, not plastic wiggling around on a loose helicoid as in Nikon's 20/2.8 AF.
This is a full-frame lens for 35mm film and full-frame digital, and will be reviewed thusly. Do not use this on cropped-frame cameras since you'll get the same or better performance for less money with any 18-55mm zoom instead. This 20mm is an ultrawide lens and shall be used as an ultrawide lens only.
This is the world's first autofocus ultrawide lens, introduced a year after the Minolta MAXXUM 7000, and it is still the best compact ultrawide lens available for the Sony Alpha Mount cameras.
These classic 20mm lenses sell every day on eBay.
Minolta Maxxum AF 20mm f/2.8. enlarge.
Format
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This is a full frame lens and I'm reviewing it as such.
It works on APS-C cameras, but you're much better off with an 18-55mm kit lens than to use this full-frame ultrawide on a crop-sensor camera.
Compatibility
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Sony
It's a Sony Alpha mount for use on cameras like the Sony A99. Everything works great, including in-camera stabilization and ultrafast AF, except that the AF-D Depth Map AF (whatever that is) and the automatic lens corrections don't work. So what, the images look great and everything else works, like face recognition and all the focus modes including Direct Manual Focus (DMF) override, so all is well.
Use it with the Sony LA-EA4 adapter and it becomes a Sony E-Mount lens for Sony's hottest mirrorless cameras!
Minolta
It's designed for Minolta's MAXXUM AF 35mm cameras.
Specifications
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Name top
Minolta calls this the MAXXUM AF 20mm f/2.8 (22).
MAXXUM is Minolta's autofocus brand, called Dynax outside the US.
The (22) is the smallest f/stop.
Optics top
10 elements in 9 groups.
Rear focus; the front and exterior of the lens never moves as focused.
Multicoated.
Diaphragm top
Minolta 20mm f/2.8 at f/22. bigger.
7 straight blades.
Stops down to f/22.
Coverage top
35mm film, full-frame and smaller format digital.
Focal Length top
20mm.
When used on an APS-C style camera, sees an angle of view similar to what a 30mm lens sees when used on a full-frame or 35mm camera.
Angle of View top
94.4º on full-frame.
Close Focus top
0.8 feet (0.25 meters or 10 inches) from the image plane.
That's about 5 inches (130mm) from the front of the lens!
Maximum Reproduction Ratio top
1:7.7 (0.13x).
Hard Infinity Focus Stop? top
Yes.
This is great for astronomy; just turn to the stop and you have fixed laboratory-perfect focus all night.
Focus Scale top
Yes.
Depth-of-Field Scale top
Yes.
Infra-Red Focus Index top
Yes.
Aperture Ring top
No.
Filter Thread top
55mm, solid alloy.
Does not move.
Size top
3.0" (76mm) diameter by 2.1 " (53 mm) extension from flange, measured.
Weight top
10.020 oz. (284.1g), actual measured.
Minolta specifies 10.1 oz. (285g).
Hood top
Hood.
Plastic bayonet hood, included.
Caps top
Minolta 20 2.8 with caps and hood. bigger.
72mm snap-in front cap and standard MAXXUM rear cap.
Case top
Often seen with a tubular case.
Quality top
Made in Japan.
Minolta Product Number top
25791.
Price, USA top
July 2017
About $225 used if you know How to Win at eBay.
May 2013
About $375 used if you know How to Win at eBay.
Performance
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Performance Compared Recommendations
Overall Autofocus Coma Distortion Ergonomics
Falloff Filters Flash Exposure Focus Breathing
Ghosts Hood Lateral Color Fringes Macro
Mechanics Sharpness Spherochromatism
Overall performance top
The Minolta 20mm f/2.8 is a classic 1980s 20mm f/2.8, performing the same optically as Nikon's plastic 20mm AF-D, but much better made mostly out of solid alloy.
This is the same lens as the cheesier Sony 20/2.8 sold today for twice the price.
Autofocus performance top
AF Speed
AF speed is ultra fast, with one full turn (two half-turns) of the AF screw bringing it from infinity down to 1.1 feet.
AF Accuracy
On the Sony A99, focus is dead-on every time at f/2.8, presuming you're letting the A99 lock-on to the right thing.
Manual Focus
Manual focus is the usual ring.
The metal ring is a bit narrow, and partially shadowed by a ridge on the barrel behind it, and so what: you can flick it with just a fingertip.
Coma performance top
Coma (saggital coma flare) often causes weird smeared blobs to appear around bright points of light in the corners of fast or wide lenses at large apertures.
Yes, the Minolta 20mm f/2.8, like other conventional 20mm f/2.8 lenses, has some coma at f/2.8.
It's completely gone by f/5.6.
Distortion performance top
The Minolta 20mm f/2.8 has the usual barrel distortion seen in similar lenses, which is a complex "moustache" distortion where the center bulges-out while the sides stay relatively straight.
The best you can do in Photoshop's lens distortion filter is to try a coefficient of +2.0 regardless of distance.
The Sony A99 doesn't recognize this lens for any automatic correction.
Ergonomics (handling and ease-of-use) performance top
Minolta 20mm f/2.8. bigger.
This lens is mostly metal, so it feels much better than the plastic garbage from Sony.
The plastic barrel is mostly rubber grip.
The solid metal focus ring has to be touched from the side, not up from the rear of the barrel because the barrel has a flare which hides the rear of the focus ring.
Falloff (darkened corners) performance top
Falloff on FX and 35mm is visible at f/2.8, and gone otherwise.
The Shading Correction in the Sony A99 makes no difference.
I've exaggerated the falloff by shooting a gray field and placing these on a gray background:
Minolta AF 20mm f/2.8 falloff on full frame and 35mm at infinity, no correction:
© 2013 KenRockwell.com. All rights reserved. |
Filters, use with performance top
Thank goodness this Minolta AF 20 has a solid alloy front end, not crappy plastic. Filters easily spin right on and off, without cross-threading.
There is no problem with vignetting on full-frame with any normal filter. With two stacked filters, you'll get a little vignetting.
It's close with a thick rotating filter like a grad.
Don't use any ultrawide with a polarizer, nature looks funny when shot that way.
The filter ring doesn't move, even with focus.
Flash Exposure performance top
This original Minolta AF 20 has no distance encoding, but that doesn't stop it from making great images with flash.
Yay Ryan! May 2013. (Sony A99, Minolta MAXXUM AF 20mm f/2.8, f/8 at 1/125 at Auto ISO 100, Sony HVL-F20AM flash.) bigger.
Focus Breathing performance top
Of interest mostly to cinematographers focusing back and forth between two subjects, the image from the Minolta 20mm f/2.8 gets larger as focused more closely.
Ghosts performance top
Ghosts are no problem with this multicoated lens, even on the complex Sony A99 which has all sorts of internal mirrors in the optical shooting shooting path.
Here's looking directly into the disk of the noonday sun, which was blinding in person:
Minolta 20mm f/2.8 at f/8. enlarge.
Enough glare to blind a dead man, and this is the worst I could show for it after several tries.
Hood performance top
Minolta 20mm f/2.8 with hood. bigger.
The plastic hood is included.
It easily bayonets on the metal bayonet.
It has a red line which stands out as you see, making it a zillion times easier to mount quickly in the field than other lenses that use the same silver-white paint for everything.
Lateral Color Fringes performance top
Lateral color fringes are this lens' biggest fault. If you look for such things, you'll see some magenta-green fringes on the 24 MP full-frame Sony A99, with lateral color correction turned OFF.
Oddly, the lateral color gets stronger if you turn correction ON in the A99! Leave the corrections OFF in the A99, since the A99 doesn't recognize this lens.
Your camera will differ.
Macro performance top
It gets exactly as close as every other 20mm f/2.8 SLR lens has for the past 30 years:
Complete image at close-focus distance at f/2.8 on full-frame.
Crop from above image at f/2.8 as shot on the 24MP Sony A99. If this is 6" wide on your screen, the complete image printed at this same magnification would be 40 x 60!" (1 x 1.5 meters!)
Thus the MAXXUM 20mm f/2.8 gets close (just 5" from the front of the lens), but since it's so wide it doesn't look that close. The great news is that it's super-sharp, even wide-open, at any distance due to the rear-focusing design.
Mechanics and Construction performance top
Minolta 20mm f/2.8. enlarge.
The Minolta 20mm f/2.8 is much better made than Sony's and Nikon's 20mm f/2.8 AF lenses. Unlike the others, this MAXXUM lens has an all-metal front end.
Filter Threads
Metal.
Hood
Plastic bayonet.
Hood Mount
Metal.
Identity Ring
Engraved metal front ring, filled with two colors of paint.
Front Barrel Exterior
Metal.
Main Barrel Exterior
Plastic.
Focus Ring
Solid metal.
Depth-of-Field Scale
Yes.
Aperture Ring
None.
Mount
Chromed metal.
Barrel Markings
Paint.
Mounting Index Dot
Red plastic ball.
Serial Number
Engraved into bottom of barrel and filled with paint.
Moisture seal at mount
No.
Noises When Shaken
Some clicking and clunking.
Made in
Japan.
Sharpness performance top
Yes, it's very sharp if you know what you're doing. Image sharpness depends more on you than your lens, and lens sharpness doesn't mean much to good photographers.
The MAXXUM 20mm's biggest limitation is lateral color. It's sharp and has a flat field otherwise.
As shot on the full-frame 24MP Sony A99:
At f/2.8
The center is sharp.
The corners are dark and somewhat blurrier. They get so much darker that I doubt anyone would notice this; the corners on full-frame aren't that bad even at f/2.8.
At f/4:
The center is perfect, and the corners are much lighter.
Now that you can see them, the corners are softer, but not that much.
At f/5.6:
The corners are even a little bit better and brighter than at f/4.
At f/5.6, this Minolta 20/2.8 is just about optimum, which is a lot more than I can say for Canon's 16-35mm f/2.8 L II and 17-40mm f/4 L which usually need to be stopped down to f/11 for best results!
At f/8
f/8 is the optimum aperture.
At f/11
It's about the same as at f/8, with the center just slightly dulled from diffraction. (Diffraction isn't as obvious in the corners since they tend to be softer.)
At f/16
It's softer all over; diffraction is limiting performance.
At f/22
It's softer all over; diffraction is limiting performance.
Spherochromatism performance top
Spherochromatism, sometimes mistakenly called "color bokeh" by laymen, is a minor aberration which can add slight color fringes to out-of focus highlights in fast, long lenses.
This lens is neither fast nor long, and I see no spherochromatism.
Sunstars performance top
Sunstar at f/22. enlarge.
With its conventional 7-bladed diaphragm, the AF 20 /2.8 can make great 14-pointed sunstars on brilliant points of light. Bravo!
Survivability performance top
This Minolta 20mm f/2.8 is from 1986 and is still working perfectly today in 2013 after having been bought from a random stranger on eBay.
It has no motors and no encoders. There is nothing to go wrong that a good repairman can't fix. The only electronics are a ROM chip that should not wear out unless you go doing something stupid, like trying to take it apart.
It is perfectly normal for the rubber on the barrel to turn white. The whiteness rubs off with use; a white looking barrel means a lens that hasn't been used much.
Therefore unlike many AF lenses today, this 20 AF ought to last last for plenty of more decades of great pictures.
Compared
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Performance Compared Recommendations
Sony's 16-35mm f/2.8 GM is a much newer, bigger and sharper lens, for Sony's E-Mount mirrorless cameras.
Sony's 12-24mm f/4 G is a newer, bigger and sharper lens, for Sony's E-Mount mirrorless cameras.
Minolta downgraded this 20mm AF to much more plastic and rounded the diaphragm, destroying sunstars some years after this model. Otherwise, it's the same thing in an obviously crappier package.
Nikon's 20mm f/2.8 AF (1989-) has always been all plastic. Its optics are about the same, and uses the same mechanical screw AF technology.
Sony's 20mm f/2.8 (2006-) is the same lens. It uses the same optics with crappier plastic mechanics, but adds a distance encoder to help flash exposure. As you've seen, flash exposure on a Sony A99 is marvelous with this lens, so you won't see me buying a new Sony version of this for twice the price!
Canon's 20mm f/2.8 USM (1992-) is a much newer kind of lens and also made with plenty of metal. Its optics are about as good, but it uses an internal ultrasonic motor and offers instant manual-focus override on all Canon EOS cameras — something none of these other lenses can do with their mechanical couplings for autofocus on their brands of cameras.
Recommendations
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Performance Compared Recommendations
I bought this Minolta 20mm f/2.8 for my Sony A99.
Today I use it with my Sony LA-EA4 adapter on my Sony full-frame mirrorless cameras.
I see no reason to pay twice as much to get a plastic version with the Sony brand on it. This classic MAXXUM lens makes great images, focuses super-fast, gives great flash exposures and feels so much better than the all-plastic copies.
On the Sony A99, turn off the lens corrections in the sixth gear menu for less lateral chromatic aberrations; the A99 adds them back in of you turn its corrections ON!
The very best protective filter is the 72mm Hoya multicoated HD3 UV which uses hardened glass and repels dirt and fingerprints.
For less money, the B+W 72mm 010 is an excellent filter, as are the multicoated version and the basic multicoated Hoya filters, but the Hoya HD3 is the toughest and the best.
Filters last a lifetime, so you may as well get the best. The Hoya HD3 stays cleaner than the others since it repels oil and dirt.
I got my 20mm at this direct link to them at eBay, see also How to Win at eBay.
This all-content, junk-free website's biggest source of support is when you use those or any of these links to approved sources when you get anything, regardless of the country in which you live. I use the stores I do because they ship from secure remote warehouses where no one gets to touch your new camera before you do. Buy only from the approved sources I use myself for the best prices, service, return policies and selection.
Thanks for helping me help you!
Ken, Mrs. Rockwell, Ryan and Katie.
© Ken Rockwell. All rights reserved. Tous droits réservés. Alle Rechte vorbehalten.
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